High-performance vertical GaN-based near-ultraviolet light-emitting diodes on Si substrates

High-performance vertical GaN-based near-ultraviolet (UV) light-emitting diodes (LEDs) on Si substrates with an electroluminescence emission wavelength of 395 nm have been fabricated by designing epitaxial structures to reduce the dislocation density and enhance the electron confinement and hole injection. By designing the epitaxial structures with a continuously Al-composition-graded AlGaN interlayer between an Al0.30Ga0.70N layer and an Al0.15Ga0.85N layer, the dislocation density in epitaxial films has been greatly reduced, and high-quality GaN epitaxial films grown on Si substrates with full-widths at half-maximum for GaN(0002) and GaN(10-12) X-ray rocking curves of 260 and 280 arcsec, respectively, have been obtained. Furthermore, by applying an electron blocking layer with 8 periods of AlInGaN/GaN superlattices, both electron confinement and hole injection have been enhanced accordingly. High-performance vertical GaN-based 395 nm UV LED chips show a high light output power of 535 mW and a low forward voltage of 3.10 V at a current of 350 mA, corresponding to a high wall-plug efficiency of 49.3%, which are the best values for GaN-based 395 nm UV LEDs ever reported. These high-performance near-UV LED chips find application in medical curing, lighting, etc.